Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/publish.yml

@@ -21,7 +21,7 @@ jobs:
     if: ${{ always() && (needs.test.result == 'success' || needs.test.result == 'skipped') }}
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
 
     - name: Install uv
       uses: astral-sh/setup-uv@v4

.github/workflows/release.yml

@@ -18,7 +18,7 @@ jobs:
       contents: write
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
       with:
         fetch-depth: 0
 

.github/workflows/test.yml

@@ -18,7 +18,7 @@ jobs:
         python-version: ["3.11", "3.12", "3.13", "3.14"]
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
 
     - name: Install uv
       uses: astral-sh/setup-uv@v4